This invention relates to graphic recording apparatus, and more particularly to cathode ray line scan recorders.
In this type of device the recording medium (e.g. light sensitive film or paper) is moved by a mechanical drive system along a path substantially normal to the display unit (e.g., a cathode ray tube). The image is recorded on the medium as it is exposed by a scanning beam from the display unit as a gray scale recorded image.
A typical recorder employs a stepper motor which moves the medium one line scan width after a previous line has been written. That technique provides a relatively slow recording rate since the delay required after each motor step to allow for medium settling time before the next line of information can be written is a factor of at least four to ten times slower than the cumulative delays of the CRT deflection system and the photographic recording speed of the medium. The recording speed of the medium in turn is dependent on two additional factors, the light sensitivity of the medium and the CRT beam intensity.
Therefore, in a situation where it is necessary to record real-time data at a rate that is faster than the medium settling rate of a stepped medium type recorder, the current systems cannot be used. The present invention overcomes that problem and allows the use of the same CRT recorder at a higher speed.